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Re: Different answers in mathematica and my calculator.

• To: mathgroup at smc.vnet.net
• Subject: [mg125655] Re: Different answers in mathematica and my calculator.
• From: Nile <thrasher300 at gmail.com>
• Date: Mon, 26 Mar 2012 01:45:57 -0500 (EST)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com

Your answer was perfect, it's exactly what I was looking for. Thank you very much.

> Am 19.03.2012 11:04, schrieb Nile:
> > 4/(3Power[2(-2)+3, (3)^-1])
> >
> > I get -(4/3) (-1)^(2/3) in Mathematica but only
> -4/3 on my calculator.
> >
> powers with non-integer exponents are not unique in
> the domain of 
> complex numbers. Try Root[]:
> 
> 4/(3 Root[#^3 - (2 (-2) + 3) &, 1])
> >
> > N[Sec[8/(8 Sqrt[2])]]/Degree to get Cos^-1 of 8/(8
> Sqrt[2]) and it gives me 75 deg instead of 45...
> >
> > I'm not sure what I'm doing wrong, I tried in
> Wolfram Alpha and it gives me the same thing.
> 
> I am afraid, you mixed the inverse function
> cos^(-1)(x) with the 
> reciprocal (cos(x))^(-1). Use ArcCos and
> FunctionExpand (the latter to 
> convert Degree to Pi/180):
> 
> ArcCos[8/(8 Sqrt[2])]/Degree // FunctionExpand
> 
> >
> > Thank you.
> >
> > -Francis
> >
> 
>